青藏公路对区域土地利用和景观格局的影响——以格尔木至唐古拉山段为例

根据1995年和2000年土地利用数据,运用ARC/INFO软件和景观生态学方法,研究了青藏公路沿线格尔木、曲麻莱、治多3个县(市)的土地利用变化和景观格局变化,修订了单一土地利用类型动态度计算公式,重点分析了公路缓冲带的土地利用变化、景观格局变化和建设用地缓冲带的土地利用变化。主要结论如下:①研究区建设用地增加迅速,林地、水域、未利用土地增加,耕地大量减少,草地退化严重,其中曲麻菜县草地减少22.8%,未利用土地增加 43.96%;②景观破碎化程度加剧,分维数、多样性指数和景观破碎度均增加;③与其它交通干线对沿线的 “轴向”影响不同,该段青藏公路以“点”型的辐射效应为标志,且仅仅影响建设用地周围的区域,格尔木市的影响范围是3 km,五道梁的影响范围是1km; ④K=(Ua+Ub－2Uc)Ua－1T-1×100%,可准确地反映单一土地利用类型变化特点。

Effects of Qinghai-Xizang Highway on Land Use and Landscape Pattern Change: from Golmud to Tanggulashan Pass

Based on digital land use maps of 1995, 2000 and road map of Resources and Environment Data Center of IGSNRR, CAS, the land use and landscape pattern change(LULPC) of Golmud, Qumaleb, Zhidoi are studied, in macro-scale, exerting Arc/GIS 8.1 and landscape ecology methods. LULPC of road buffer zones and the bound of construction land expansion is stressed. The conclusions are given as follows: 1. Prominent changes have taken place in land use and landscape pattern from 1995 to 2000. (a) Woodland area increased 0.4%, grassland area reduced 6.26%, water area increased 7.17%, construction land area increased 323.8%, unused land area increased 6.96%, cultivated land area reduced 51.43%. Especially, land degraded seriously, grassland area reduced 22.8% and unused land area increased 43.96% in Qumaleb. (b) The comprehensive land use dynamic degree is 2.25 and the land use dynamic degree of construction land is the biggest, while cultivated land takes the second place and woodland takes the least. (c) The land use degree comprehensive index is 195.2 in 1995, and 156.4 in 2000, reduced 38.8. The fundamental reason is that a great deal of grassland had been transformed into unused land in 5 years. (d) Landscape changed dramatically. The sum of patches increased 1999 and the landscape fragmentation degree increased from 0.115 to 0.124, showing the enhancement of land fragmentation degree. The diversity index increased from 1.308 to 1.331, implying the enhancing of landscape heterogeneity. The fractal degree increased from 1.453 to 1.456 and the shape of patches got complicated. 2. Differed from the corridor effect of other traffic main lines, the corridor effect of this section of road is not obvious and its“point”radiation effect can be seen easily. (a) The land use degree comprehensive index of road buffer zones dropped except the 1 km zone, 40-45 km zone and 50-60 km zone. The land use dynamic index enhanced when the distance to the road get longer, obviously differing from other study areas due to sparse population and sluggish economic development. The landscape diversity index and fractal dimension has no relationship with the distance to the road. (b) The expanding range of Golmud City is confined in 3 km buffer, for Wudaoliang buffer, it is 1 km. No land use change happened in Nanshankou buffer. 3. The new formula ( K = (U_a +U_b - 2U_c) U_a ^-1T^-1 ×100% ) is used to nicely define the land use dynamic degree exactly.